Promotion of Direct Methanol Electro-oxidation by Ru Terraces on Pt by using a Reversed Spillover Mechanism

Abstract

By examining Pt-core-Ru-shell nanocatalysts of different compositions for the electro-oxidation of methanol, a volcano activity response is revealed according to Ru coverage. This activity profile can be accounted for by a bifunctional mechanism of spilling over the hydroxy species from Ru to Pt in close proximity with supplemental electronic and structural promotions. At high surface coverage of Ru on Pt, it is revealed that a new 'direct' pathway of Ru terraces on Pt sites in close vicinity can provide synergetic catalysis. Pt sites activate the methoxy surface species, which migrate to the Ru terrace to react with its surface oxygenates, from water dissociation, for accelerated CO2 formation through a 'reversed' spillover mechanism. This non-CO electro-oxidation route to CO2 on a Ru surface requires a lower potential to take place than the corresponding process on a Pt surface. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.